Method for the preparation of compounds having boron-sulfur bonds



United States Patent METHOD FOR THE PREPARATION OF COM- POUNDS HAVING BORON-SULFUR BONDS Robert J. Brotherton, Fullerton, and Lowell L. Petterson, Whittier, Calif., assignors to United States Borax & Chemical Corporation, Los Angeles, Calif., a corporation of Nevada No Drawing. Filed Sept. 30, 1959, Ser. 'No. 843,355

Claims. (Cl. 260-462) The present invention relates as indicated to the preparation of compounds having boron-sulfur bonds.

The instant invention is predicated upon the discovery that the nitrogen atom of any compound having boronnitrogen bonds can be displaced from the boron by the use of an acid in the presence of a mercaptan.

Thioborates produced according to the present process have utility as agents for imparting improved properties to lubricants. The use of present day highly refined oils has caused severe corrosion problems with the hard metal alloy bearings used in high compression engines. The corrosion to hard metal alloy bearings by highly refined lubricating oils can be inhibited by adding to such oils from about 0.01% to about 3.0% of one of the thioborates produced by the present process.

It is therefore the principal object of this invention to provide a new and noval method for producing thioborates.

A further object is to provide a method for producing thioborates which is economical and eflicient.

Other objects will appear as the description proceeds.

To the accomplishment of the foregoing and related ends, the invention then comprises the features hereinafter fully described and pointed out in the claims, the following description setting forth in detail certain illustrative embodiments of the invention, these being indicative, however, of but a few of the ways in which the principle of the invention may be employed.

Broadly stated, the present invention comprises the method of producing thioborates which comprises reacting an aminoborane with at least stoichiometric amounts of a mercaptan and an acid, said aminoborane selected from the class consisting of primary and secondary trisalkylaminoboranes having alkyl groups of 1 to 6 carbon atoms and primary trisarylaminoboranes, said aryl group selected from the class consisting of phenyl and methyl substituted phenyl, said mercaptan selected from the class consisting of alkyl mercaptans having alkyl groups of 1 to 6 carbon atoms and aryl mercaptans, said aryl groups selected from the class consisting of phenyl, methyl substituted phenyl and naphthyl and said acid selected from the class consisting of HCl, HBr, HF and H 80 From the foregoing broadly stated paragraph it will be seen that at least stoichiometric amounts of reactants are necessary to the present process. From the following general equation it will be seen that at least three moles of mercaptan and at least three moles of acid per mole of aminoborane are necessary. Thus it will be clearly understood that more than three moles of each of the mercaptan and acid can be used and in no way is the excess detrimental to the process. However, it will also be readily seen that a large excess of reactants would be economically undesirable.

2,960,530 Patented Nov. 15, 1960 It is immaterial to the present process whether the reaction is conducted in the presence or absence of 'a solvent. If no solvent is used then an excess of one of the above reactants can be efiectively used as a solvent. Or, if desired, a solvent such as aliphatic and aromatic hydrocarbons, ethers, chlorinated aliphatic and aromatic hydrocarbons, etc., can be used.

The following is a partial enumeration of reactants applicable to the present process:

Primary aminoboranes:

Tris(methylamino)borane Tris (ethylamino borane Tris n-propyl amino) borane Tris isopropylamino borane Tris(n-butylamino)borane Tris(isobutylamino)borane Tris(n-amylamino)borane Tris(sec-arnylamino)borane Tris n-hexylamino borane Tris sec-hexylamino borane Tris(anilino)borane Tris(p-toluidino)borane Secondary aminoboranes:

Tris(dimethylamino)borane Tris diethylamino borane Tris (di-n-propylarnino) borane Tris(diisopropylamino)borane Tris(di-n-buty1amino)borane Tris(diisobutylamino)borane Tris (di-namylarnino borane Tris-(di-sec butylamino)borane Tris(di-n-hexylamino)borane Tris(di-sec-hexylamino)borane Tris pyrrolo borane Mercapt-ans:

Methyl mercaptan Ethyl mercaptan n-Propyl mercaptan Isopropyl mercaptan n-Butyl mercaptan Isobutyl mercaptan n-Amyl mercaptan n-Hexyl mercaptan Phenyl mercaptan Tolyl mercaptans Naphthyl mercaptans Acids:

Hydrogen fluoride Hydrogen chloride Hydrogen bromide Sulfuric So that the present invention can be more clearly understood, the following examples are given for illustrative purposes:

A solution of 7.16 grams of methyl mercaptan and 6.20 grams of tris(dimethylamino)borane in 15 ml. of diethyl ether was cooled to about --40 C., and 4.74 grams of HCl in 65 ml. of diethyl ether was added with stirring over a 15-minute period. The reaction mixture was warmed to 0 C. during the addition of the acid and was held at this temperature for 45 minutes. The reaction mass was then warmed to room temperature over a 1.5-hour period and the solid dimethylamine hydrochloride removed by filtration. The solvent was separated by fractional distillation of the filtrate and the resulting residue was distilled at atmospheric presn 1.5601; B, 7.19% (B, 7.11% calculated).

A solution of 7.9 grams of tris(di-n butylaminmborane and 6.7 grams of hexyl mercaptan in 10 ml. of diethyl ether was cooled to about -30 C., and 4.9 grams of :HBr in 50 ml. of diethyl ether was added with stirring over a 20-minute period. The reaction mixture was warmed to C. during the addition of the acid and held at this temperature for about 30 minutes. The reaction mass was warmed to room temperature over a one-hour period and the di-n-butylamine hydrobromide removed by filtration. The solvent was distilled from the filtrate and the resulting residue was distilled at reduced pressure to yield tri-n-hexyl-thioborate.

III

A solution of 4.0 grams of tris(methylamino)borane and 15.0 grams of benzyl mercaptan was cooled to --40 C., and 4.4 grams of HCl in 50 ml. of diethyl ether was added with stirring over a 15-minute period. The reaction mixture was warmed to 0 C. during the addition of the acid and held at this temperature for 45 minutes. The mass was then warmed to room temperature over a two-hour period and the methylamine hydrochloride was removed. The solvent was distilled from the filtrate and the resulting solid residue was recrystallized from petroleum ether to yield tribenzylthioborate.

Other modes of applying the invention may be employed, change being made as regards the details described, provided the features stated in any of the following claims or the equivalent of such be employed.

We, therefore, particularly point out and distinctly claim as our invention:

1. The method of producing thioborates which comprises reacting an aminoborane with at least stoichiometric amounts of a mercaptan and an acid, said aminoborane selected from the class consisting of primary and secondary trisalkylaminoboranes having alkyl groups of l to 6 carbon atoms and primary trisarylaminoboranes said aryl group selected from the class consisting of phenyl, and methyl substituted phenyl, said mercaptan selected from the class consisting of alkyl mercaptans having alkyl groups of 1 to 6 carbon atoms and aryl mercaptans said aryl groups selected from the class consisting of phenyl, methyl substituted phenyl and naphthyl, and said acid selected from the group consisting of HCl, HBr, HF and H 2. The method of producing thioborates according to the general reaction wherein B(NR is an aminoborane selected from the class consisting of primary and secondary trisalkylaminoboranes having alkyl groups of 1 to 6 carbon atoms and primary trisarylaminoboranes said aryl group selected from the class consisting of phenyl and methyl substituted phenyl, R'SH is a mercaptan selected from the class consisting of alkyl mercaptans having alkyl groups of 1 to 6 carbon atoms and aryl mercaptans said aryl group selected from the class consisting of phenyl, methyl substituted phenyl and naphthyl and HX is an acid selected from the group consisting of HCl, HBr, HF and H 3. The method of producing trimethylthioborate which comprises reacting at least three moles of methyl mercaptan with at least three moles of HCl per mole of 'tris (dimethylamino) borane.

4. The method of producing tri-n-hexylthioborate which comprises reacting at least three moles of n-hexyl mercaptan with at least three moles of HBr per mole of tris (di-n-butylamino) borane.

No references cited. 

1. THE METHOD OF PRODUCTING THIOBORATES WHICH COMPRISES REACTING AN AMINOBORANE WITH AT LEAST STOICHIOMETRIC AMOUNTS OF A MERCAPTAN AND AN ACID, SAID AMINOBORANE SELECTED FROM THE CLASS CONSISTING OF PRIMARY AND SECONDARY TRISALKYLAMINOBORANES HAVING ALKYL GROUPS OF 1 TO 6 CARBON ATOMS AND PRIMARY TRISARYLAMINOBORANES SAID ARYL GROUP SELECTED FROM THE CLASS CONSISTING OF PHENYL,AND METHYL SUBSTITUTED PHENYL, SAID MERCAPTAN SELECTED FROM THE CLASS CONSISTING OF ALKYL MERCAPTANS HAVING ALKYL GROUPS OF 1 TO 6 CARBON ATOMS AND ARYL MERCAPTANS SAID ARYL GROUPS SELECTED FROM THE CLASS CONSISTING OF PHENYL, METHYL SUBSTITUTED PHENYL AND NAPHTHYL, AND SAID ACID SELECTED FROM THE GROUP CONSISTING OF HCL, HBR, HF AND H2SO4. 